CYTOTOXIC DITERPENOID CONSTITUENTS FROM ANDROGRAPHIS-PANICULATA NEES LEAVES

In our search for antineoplastic constituents from Thai medicinal plan ts, the methanolic extract from the leaves of Andrographis paniculata Nees. (Acanthaceae), known as ''Fha Talai Joan'', was found to show si gnificant cytotoxicity against KB and P388 cells, Bioactivity guided c hromatographic fractionation has led to the isolation of three diterpe noids. Interestingly, andrographolide, a major constituent, has been s hown for the first time to have potent cytotoxic activity against KB c ells cultures as well as P388 lymphocytic leukemia, whereas 14-deoxy-1 1,12-didehydroandrographolide and neoandrographide have shown no cytot oxic activity in the tumor cell lines. In addition, stigmasterol was i solated from the hexane extract of this plant. The structures of the i solated compounds were elucidated by spectroscopic data.